While most vehicles are typically equipped with safety devices to protect vehicle occupants in the event of a side impact occurring. In general, in a sideways direction the distance between a vehicle occupant and the exterior of the vehicle is relatively small, since the sides of the vehicle are thin. It is therefore important that safety devices, such as internal side air-bags, which are adapted to protect occupants during side impacts, are activated at the earliest possible stage.
In some instances, it is possible to detect that a side impact is imminent, for instance by using radar or lidar detection, and to activate one or more appropriate vehicle safety systems before the impact has occurred. In other circumstances, impact sensors are used to detect side impacts, and hence deployment of the vehicle safety systems will not occur until the impact has actually happened.
Deployment of the safety systems will be controlled by an on-board processor, in accordance with a deployment algorithm. There are, however, competing priorities which must be taken into account when formulating the algorithm. On the one hand, as discussed above, the relevant side impact safety systems must be activated as swiftly as possible in the event of a crash situation occurring. On the other hand, the algorithm must be robust against “false positive” determinations, which could lead to the side impact safety systems being deployed unnecessarily. Such situations may include the door of a vehicle being slammed with above average force, and low-impact crashes that are unlikely to cause harm to vehicle occupants. It will therefore be understood that deployment algorithms are generally a compromise between these two competing priorities.
It is an object of the present invention to seek to provide an improved safety system of this type.
Accordingly, one aspect of the present invention provides a vehicle safety system comprising: at least one occupant safety device for protecting an occupant of the vehicle in the event of a side impact; and a control unit operable to receive information from one or more vehicle sensors and to provide a trigger signal to activate the occupant safety device, wherein: under normal driving conditions, a default deployment algorithm is used by the control unit to determine whether the trigger signal should be generated; and if it is determined that loss of control of the vehicle is occurring, or is expected to occur, and the longitudinal speed of the vehicle exceeds a first threshold, the control unit employs a first further deployment algorithm to determine whether the trigger signal should be generated, the first further deployment algorithm being adapted to cause the trigger signal to be generated a shorter time after the initiation of a side impact than is the case for the default deployment algorithm.
Advantageously, it is determined that loss of control of the vehicle is occurring, or is expected, if it is determined that the vehicle is undergoing one or more of understeer, oversteer, a lateral skid, avoidance manoeuvring, emergency braking, and departure from the road on which the vehicle is travelling.
Preferably, the control unit is provided with criteria for evaluating whether one or more of understeer, oversteer, lateral skid avoidance manoeuvring, emergency braking, or road departure are occurring, from signals generated by the one or more vehicle sensors.
Conveniently, a second further deployment algorithm is adopted if both the longitudinal and lateral speeds of the vehicle exceed respective thresholds, and it is determined that loss of control of the vehicle is occurring, or is expected to occur.
Advantageously, the second further deployment algorithm is adapted to cause the trigger signal to be generated a shorter time after the initiation of a side impact than is the case for the first alternative deployment algorithm.
Preferably, the preset threshold for vehicle speed is between 5 and 20 km/h.
Conveniently, the preset threshold is 15 km/h.
Another aspect of the present invention provides a method of controlling an occupant safety device of a vehicle for protecting an occupant of the vehicle in the event of the side impact, the method comprising the steps of: receiving information from one or more vehicle sensors; and analysing the signals in accordance with a deployment algorithm and providing a trigger signal to activate the occupant safety device if it is determined that activation of the safety device is necessary, wherein: under normal driving conditions, a default deployment algorithm is employed to determine whether the trigger signal should be generated; and if it is determined that loss of control of the vehicle is occurring, or is expected to occur, and the longitudinal speed of the vehicle exceeds a first threshold, employing a first further deployment algorithm to determine whether the trigger signal should be generated, the first further deployment algorithm being adapted to cause a trigger signal to be generated a shorter time after the initiation of a side impact than is the case for the default deployment algorithm.
A further aspect of the invention provides a computer program comprises computer program code adapted to perform all of the steps as claimed above wherein the program is run on a computer.
Another aspect of the invention provides a computer program as claimed above is embodied on a computer readable medium